This invention relates to a magnetically actuated eccentric motion motor having an armature which rolls within a stator.
Electric motors typically consist of a fixed stator and a rotatable armature, between which electromagnetic forces are produced to cause the armature to rotate. The armature is mounted or carried by bearings to maintain a certain spacing between the armature and the stator and this, of course, gives rise to friction. Also, the further the spacing between the armature and stator, the weaker are the electromagnetic forces.
A number of proposals have been made for a motor or actuator in which an armature or roller rolls inside a cylindrical cavity as a result of electromagnetic forces. The electromagnetic forces are produced in some sequence along the perimeter of the cavity to attract the armature which is made of a ferromagnetic material. See, for example, U.S. Pat. Nos. 2,561,890, 4,728,837 and 4,482,828, German Pat. No. DAS 1132229 and Swiss Pat. No. 159,716. Disadvantages of such prior art mechanisms are that the mechanisms are generally quite bulky and heavy, are not easily miniaturized, and have low energy densities. This bulkiness and weight arises from the need of mechanism components capable of developing sufficient electromagnetic forces to properly operate the mechanism.
Electrostatic motors likewise generally include a stator and armature mounted to rotate near or within the stator, where the forces of attraction therebetween are electrostatic rather than electromagnetic. Examples of electrostatic motors are shown in U.S. Pat. Nos. 735,621, 3,297,888, 3,517,225 and 4,225,801. In a recently issued U.S. Pat. No. 4,922,164, an eccentric motion, electrostatic motor is described in which a cylindrical armature is disposed in rolling engagement with a hollow cylindrical stator. Elongate conductive strips are disposed in the inside wall of the hollow of the stator and are circumferentially spaced about the hollow. The conductive strips successively receive electrical charges to thereby attract the armature and cause it to roll in the hollow of the stator.
Electrostatic motors are generally lighter in weight and potentially smaller in size than electromagnetic motors, but the attractive forces are generally weaker.